A Ca(H₂PO₄)₂/RM composite powder suppressant with core–shell structure was prepared with modified red mud (RM) as the carrier and Ca(H₂PO₄)₂ as the loaded particles, using a solvent–antisolvent process, in an attempt to suppress aluminum dust explosion more effectively. The suppression effects of the Ca(H₂PO₄)₂/RM composite powder suppressant for aluminum dust flame propagation and for explosion overpressure were tested in a vertical glass tube test apparatus and a 20 L explosion vessel. The results show that the Ca(H₂PO₄)₂/RM composite powder suppressant was more effective in suppressing aluminum dust flame propagation and explosion overpressure than either Ca(H₂PO₄)₂ or RM powder alone. Finally, the suppression mechanism of the Ca(H₂PO₄)₂/RM composite powder suppressant was analyzed. On the one hand, a large amount of burning heat was absorbed through the decomposition of Ca(H₂PO₄)₂ and the melting phase transformation of the decomposition product; on the other hand, the strong isolation provided by the RM helped limit flame propagation. The strong adsorptivity of RM allowed this material to adsorb the radicals from the explosion reaction perfectly.

In this paper, NaHCO₃/kaolin composite powder explosion suppressor was prepared by antisolvent-dissolution method. The effect of NaHCO₃/kaolin composite powder explosion suppressor on aluminum powder explosion was studied by Hartmann tube and 20 L spherical explosion tank. The propagation suppression experiment shows that as the content of the NaHCO₃/kaolin composite powder inhibitor increases, the explosion flame propagation length and speed gradually decrease. When 50% (by mass) NaHCO₃/kaolin composite powder inhibitor is added, the flame propagation of aluminum powder is suppressed. The experiment of suppressing the explosion of aluminum powder with a composite powder suppressant was carried out in a 20 L spherical explosion tank. The results show that the addition of 75% (by mass) NaHCO₃/kaolin composite powder suppressant can achieve complete explosion suppression of aluminum powder. By comparing NaHCO₃ powder, kaolin powder and composite powder detonator, the composite powder detonator has a better effect on suppressing the flame propagation and explosion pressure of aluminum powder than the monomer powder does. The mechanism of the explosion suppression of aluminum powder by the NaHCO₃/kaolin composite powder inhibitor was analyzed.